When you work for yourself you generally have your employer withhold federal and state (if applicable) income taxes from your wages. Then at the end of the year it becomes a calculation of if you had enough withheld (i.e. you get a refund) or have to make a balance due payment.
But what if you work for yourself (i.e. self employed) and no one is “withholding” anything from your check? Then this post will clue you in on how you make your pay